Direction radio transmitting system



HJRTRANsM ITTER H .F'. RECEIVER W P. LEAR DIRECTION RADIO TRANSMITTING SYSTEM Original Filed Aug. 25, 1939 MODULATOR AMPLIFIER R-HTHANSMITTER INVENTOR. uffllliqm 3? @eav Fig! 5 Patented May 8, 1945 UNITED sr OFFICE v DIRECTION RADIO TRANSMITTING SYSTEM William 1?. Lear, North Hollywood, Calif., assignor, by mesne assignments, to Lear, Incorporated, Piqua, Ohio, a corporation of Illinois 14 Claims.

This invention relates to signal transmitting arrangements for radio guidance systems, and more particularly relates to such arrangements in which the radiation of a plurality of radio transmitters is successively switched on and off. This caseis a division of my copending application entitled Radio guidance system, Serial No. 291,807 filed August 25, 1939, which is assigned to the same assignee as the present case.

In accordance with my present invention I provide a radio transmitting arrangement including two spaced non-directional transmitter stations having the same carrier frequency. The radiation of the stations is successively switched on and off at predetermined intervals. The respective signals of the two stations are differentiated either with separate audio frequency modulations, or with tone modulation of one signal, the other signal being unmodulated. Switching means controlled by a constant speed motor are employed for successively connecting and disconnecting a high frequency transmitter associated with one station with its antenna. The thus produced intermittent signal is picked up by the second transmitter station and causes the latter to radiate alternately with the first station in dependence upon the received high frequency signal.

The signal transmitting arrangement of the present invention may find particular application in connection with the radio guidance receiver systems disclosed in my copending application above referred to. The receiver systems disclosed therein comprise means for automatically deriving and maintaining an individual directional bearing on each of the radio signals radiated by two transmitter stations. To provide an instrument approach system, two nondirectional transmitters are spaced from each other and arranged in line with the desired runway or approach path. The pilot of an airplane or other mobile craft is thus continually made aware of his position. Other fields of application of the signal transmitting arrangement of the present invention will be readily apparent to those skilled in the art.

It is accordingly an object of my present invention to provide novel radio signal transmitting arrangements including means for successively effecting signal radiation from several transmitters.

Another object'of the invention is to provide two spaced non-directional radio transmitter stations, one of which produces an intermittent control signal for successively switching on and oiT the second transmitter station.

These and further objects of my present invention will become apparent in the following de scription of an exemplification thereof shown in the accompanying drawing, in which:

Fig. 1 is a schematic electrical diagram of the arrangement at one of the transmitter stations of the present invention.

Fig. 2 is a schematic electrical diagram of the arrangement at the second transmitter station.

Fig. 3 shows curves illustrating the electric switching operation for the two transmitter stations of Figs. 1 and 2.

Referring to the drawing, Fig. 1 is a schematic arrangement corresponding to one of the transmitters here designated as T1; and Fig. 2 to the other, T2. The transmitter stations of Figs. 1 and 2 both have the same carrier frequency. Transmitting antenna I0 is designed to efiiciently radiate the radio frequency signal of T1. Any suitable carrier frequency may be used such as a commercial frequency, a broadcast frequency, if permissible, a high frequency, or even an ultrahigh frequency. A carrier frequency of, for example, 209 kilocycles may be used for T1 and T2. Similarly, a frequency of say 1614 k'ilocycles may be used, or 4790 cycles, etc.

The radio frequency generator for T1 isschematically indicated within dotted rectangle ll. Radio frequency oscillator l2 generates the carrier at the preferred radio frequency. An audio frequency oscillator I3 generates the tone signal for modulating the radio frequency carrier. The tone or audio frequency is used to distinguish the radiation of station T1 from that of station T2.

The audio frequency of generator l3 may be '75 cycles, cycles or higher as desired. The radio frequenoycarrier is modulated by the audio frequency tone at radio frequency modulator I4, the output of which is connected to radio frequency amplifier 15. The output of amplifier i5 is connected to loading coil l6 and in turn to antenna 50. Loading coil I6 is adjusted for most efficient radiation of the radio frequency wave through antenna It].

An arrangement is provided for maintaining the transmission of the modulated radio frequency wave through antenna 0 for a predetermined period, in the range say of one-third to one-half of a second; extinguishing the transmission of the radio signals corresponding to H at station T1; and successively providing for the transmission of the radio frequency signal from the other station T2, of Fig. 2. To this end,

a high frequency relaying transmitter fl is arranged to radiate from antenna Iii to control remote transmitter T2. Transmitter I7 radiates while transmitter II is extinguished and vice versa.

In the system of Fig. l, I employ the same antenna It for the transmission of both the modulated radio frequency wave from transmitter II as well as the high frequency relaying signal from unit I'l. Separate antennae may be used. The output of transmitter I1 is connected to back contact I8 of relay armature 26 through a loading coil 2I. When relay armature connects with back contact it, high frequency transmitter I1 is connected to antenna I0. Loading coil 2! is adjusted for most efilcient radiation of the high frequency wave from antenna II). To insure the proper extinguishing of the radiation from both transmitters, I prefer to disconnect the positive B potential supply 22 from the transmitters during their respective non radiating periods. For this purpose, I use relay armature 23 connected to B supply 22 which is connected to radio frequency generator I I through relay contact 2 3 and lead 26 as shown schematically. Common B supply 22 is also connectable to high frequencytransmitter ll through relay contact when armature 23 contacts therewith upon energization of solenoid 27.

In the described switching-over arrangement for stations T1 an T2, any time lag due to the action of relays or other components should be properly designed and arranged to give the indicated mode of operation. To simplify the exposition, no lag will be assumed. However, suitable construction in practice to accomplish the desired results will be apparent to those skilled in the art. The design of the commutators, cams or other switch-over means should be such as to take into account the lag in the connection and disconnection of the circuits by the relays and associated armatures.

Relay solenoid 2T issuitably energized at the proper time intervals to attract relay armatures 20 and 23 from their normal upper position shown, to the lower contact position for correspondingly extinguishing the generation and transmission of the radio frequency signal of unit II and initiating the generation and transmission of the high frequency relay signal of unit I'I through the antenna, Ill successively and without overlapping. A preferred transmission and cessation interval in practice is one-third of a second where the transmitter stations are used for aircraft guidance. However, it is to be understood'that different intervals, such as one-half second or greater are equally suitable, as are intervals of less than one-third second also feasible. If the transmitter system is used for marine guidance longer intervals are useful since the approach speed of the vessel to be guided is considerably less.

An arrangement for periodically energizing relay solenoid 21 to effect the successive switching at predetermined intervals is diagrammatically illustrated in Fig. 1. The timing intervals are equal and cyclic, not necessarily absolute in value, but generally within the predetermined timing interval desired. A constant speed motor 30 is energized through a local potential source 3|, such as a 12 volt battery. An alternating current motor and supply also may be used. Motor 30 drives disk 32 through suitable reduction gearing 33, 34. A pin 35 projects from the face of disk 32. A star wheel 36 is arranged to coact with pin 35 on each revolution of disk 32.

Star wheel 36 is advanced through an are equal to the width of one of its teeth during each revolution of disk 32. The speed of motor 30 as well as the ratio of the respective gearings 33, 34 and 35, 36 is designed so as to advance the commutator 31 by one segment corresponding to one switching interval; in one-third of a second in the present case.

Commutator 3i comprises switch arm or blade 38 rotatable over a plurality of equi-spaced contact segments 48. Alternate segments 40 are connected together by connections leads 41 and in turn connected to relay solenoid 21 through lead 42. Switch arm 38 iselectrically insulated from contacts 40 and is connected to one, side of the potential source, namely battery 3|. Switch arm 38 is shown on one of the insolated cont acts. The motivation of switch arm 38 is by star wheel 36 interconnected through shaft 43. The battery circuit through relay 21 and ground is open during such position. When switch arm 38 engages one of the four interconnected contact elements 40 of commutator 31, relay 21 is energized by battery 3| to attract armatures 20 and 23 to the downward or front contact position.

Armatures 20 and 23 are normally biased upwards towards their back contacts 44 and 24, respectively maintaining transmitter II energized and connected for radiation through antenna iii. When relay 21 is energized, armatures 20 and 23 are'attracted to front contacts I8 and 25, respectively, energizing high frequency relaying transmitter I1 and connecting it to antenna It for radiation. During this interval, radio signal transmitter II is deenergized and not transmitting, through disconnection of B supply 22 therefrom. Constant speed motor 30 causes star wheel 36 to advance one segment for every predetermined interval. Commutator arm 38 accordingly is moved to successively cause energization and deenergization of relay 2'! resulting in corresponding alternate transmission of modulated radio signal from unit I I and high frequency relaying signal from unit II.

While transmitter unit I I is quiescent and high frequency relay transmitter I1 is radiating from adjustable loading coil 55, front relay contact 56,

and relay armature 51. Positive B supply 58 is connectible to radio frequency transmitter 53 through contact and armature 6| of relay 52. Energization of solenoid 52 by receiver 50 during the high frequency relaying period causes the attraction of armatures 51 and 6 I against front relay contacts 56 and 60, respectively. This energizes radio frequency transmitter 53 with B supply 58 and connects the output of transmitter 53 to antenna 54 for radiation.

Radiofrequency transmitter 53 preferably has the same carrier frequency as transmitter unit I I of Fig. 1, corresponding to the frequency of oscillator I2. Although audio frequency modulation of radio frequency transmitter 53 may be used, I prefer to employ no modulation of the signal from transmitter 53 but transmit a continuous wave signal instead.

Fig. 3 shows curves illustrating the relative periods of transmission of stations T1 and T2 to give the radio guidance signals. The equally spaced rectangular curves represent the uniform duration of transmission of the radio frequency signals. Signal transmission period a of station T1 is-equivalent to the cessation of transmission period a of station T2. Similarly, cessation of transmission period b of station T1 corresponds to the duration of transmission period b of station T2. Signal transmission from both stationsTi and T2 is at the maximum amplitude during radiation. In the transmission systems of Figs. 1 and 2, stations T1 and T2 have the same radio frequency carrier, the signal from station T1 being modulated with an audio frequency signal such as 75 cycles and that from station T2 being continuous wave. It is not necessary to have the stations T1 and T2 radiate for the full indicated intervals. However, simultaneous transmission of Ti and T2 should not occur when a common carrier frequency and only one distinguishing modulation signal is used.

Various changes and modifications may be made to the details of construction of the invention without departin from the broader spirit and scope thereof, and accordingly,'I do not intend to be limited except as set forth in the following claims.

I claim:

1. A radio guidance system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, means for successively efiecting radiation of radio signals by said first and relaying transmitters for predetermined intervals, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, and means connected to said radio receiver for effecting radiation of radio signals from said second transmitter during reception of said relaying radio signals.

' 2. A direction radio transmittingsystem comprising a first transmitter of radio frequency signals, a second transmitter remotely situated from said first transmitter and having means for generating radio signals of substantially the same carrier frequency as the signals radiated by said first transmitter, a relaying radio frequency transmitter located at said first transmitter, means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, and means connected to said radio receiver for effect ing radiation of radio signals from said second transmitter during reception 5 of said relaying radio signals.

3. A direction radio transmitting system comprising a first transmitter of radio frequency signals, a second transmitter remotely situated from said first transmitter and having means for generating radio signals of substantially the same carrier frequency as the signals radiated by said first transmitter, one of said radio frequency signals being modulated, a relaying transmitter of high frequency radio signals located at said first transmitter, means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, and means connected to said radio receiver for effecting radiation of radio signals from said second transmitter during the period of reception of said relaying radio signals.

4. A radio guidance system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, periodically actuated means including a relay unit and switches in circuital connection with said first and relaying transmitters operated by said relay unit for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, and means connected to said radio receiver for effecting radiation of radio signals from said second transmitter during th period of reception of said relaying radio signals.

5. A radio guidance system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, a relay unit, means for periodically energizing and deenergizing said relay unit for predetermined intervals, switches operated by said relay unit and connected with said first and relaying transmitters for successively effecting radiation thereof, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, a relay connected to said radio receiver, and switching means arranged for operation by said relay and connected in circuit with said second transmitter for effecting radiation of radio signals from said second transmitter during the period of reception of said relaying radio signals.

6. A direction radio transmitting system com prising a first transmitter of radio frequency sig nals, a second transmitter f radio frequency signals remotely situated from said first trans- ,radio signals radiated from said relaying transmitter, and means connected to said radio receiver for efiecting radiation of radio signals from said second transmitter during the period of reception of said relaying radio signals.

.7. A direction radio transmitting system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, a constant speed motor, a commutator'having spaced insulated contacts, a rotary switch arm engageable with said contacts and driven by said motor, a relay connected with alternate contacts on said commutator, said switch arm being connected with a current source for energizing said relay-for predetermined intervals, switches operated by said relay for alternately effecting radiation of radio signals by said first and relaying transmitters in dependence upon the motivation of said switch arm, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, and means connected to, said radio receiver for effecting radiation of radio signals from said second transmitter during the period of reception of said relaying radio signals.

8. A direction radio transmitting system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, a constant speed motor, a relay, a periodic switching means driven by saidmotor and in electric circuit relation with said relay and a current source for energizing said relay for predetermined intervals, switches in circuital connection with said first and relaying transmitters and operated by said relay for successively effecting radiation of radio signals by said first and relaying transmitters, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, a second relay associated with said radio receiver and operable thereby during reception of radio signals from said relaying transmitter, and switch means arranged for operation by said second relay and connected in circuit with said second transmitter for effecting radiation of radio signals therefrom during the period of reception of said relaying radio signals.

9. A direction radio transmitting system comprising a first transmitter of radio frequency signals, a second transmitter of radio frequency signals remotely situated from said first transmitter, a relaying radio frequency transmitter located at said first transmitter, a constant speed motor, a commutator having spaced insulated contacts,

rotary switch arm engageable with said contacts and driven by said motor, a relay connected with alternate contacts on said commutator, said switch arm being connected with a current source for energizing said relay for predetermined intervals, switches operated by said relay for alternately effecting radiation of radio signals by said first and relaying transmitters in dependence upon the motivation of said switch arm, a radio receiver located at said second transmitter responsive to radio signals radiated by said relaying transmitter, a second relay associated with said radio receiver and operable thereby during re ception of radio signals from said relaying transmitter, and switch means arranged for operation by said second relay and connected in circuit with said second transmitter for effecting radiation of radio signals therefrom during the period of reception of said relaying radio signals.

10. A signal transmission arrangement for a radio guidance system comprising a first transmitter of radio frequency signals; a second transmitter of radio frequency signals remotely situated fromsaid first transmitter; a relaying radio frequency transmitter located at said first transmitter; a common antenna for said first transmitter and said relaying transmitter; means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals and including a device for successively connecting said first transmitter and said relaying transmitter to said antenna during such predetermined intervals; a radio receiver located at said second transmitter and responsive to signals radiated by said relaying transmitter; and means connected to said receiver for effecting radiation of signals by said second transmitter during the period of reception of said relaying radio signals.

11. A signal transmission arrangement for a radio guidance system comprising a first transmitter of radio frequency signals; a second transmitter of radio frequency signals remotely situated from said first transmitter; a relaying radio frequency transmitter located at said first transmitter; means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals; mechanism for positively interrupting radiation of said first transmitter when said relaying transmitter is radiating and of said relaying transmitter when said first transmitter is radiating; a radio receiver located at said second transmitter and responsive to signals radiated by said relaying transmitter; and means connected to said receiver for effecting radiation of signals by said second transmitter during the period of reception of said relaying radio signals.

12. A signal transmission arrangement for a radio guidance system comprising a first transmitter of radio frequency signals; a second transmitter of radio frequency signals remotely situated from said first transmitter; a relaying radio frequency transmitter located at said first transmitter; a common antenna for said first transmitter and said relaying transmitter; means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals and including a device for successively connecting said first transmitter and said relaying transmitter to said antenna during 4 such predetermined intervals and for successively Ill disconnecting said first transmitter and said relaying transmitter from said antenna during the period when either thereof is not effective to radiate signals; a radio receiver located at said second transmitter and responsive to signals radiated by said relaying transmitter; and means connected to said receiver for effecting radiation of signals by said second transmitter during the period of reception of said relaying radio signals.

13. A signal transmission arrangement for a radio guidance system comprising a first transmitter of radio frequency signals; a relaying radio frequency transmitter locatedat said first transmitter; a common antenna for said first transmitter and said relaying transmitter; a B-power supply located at said first transmitter; a device for successively connecting each of said transmitters to said antenna and said B-power supply for a predetermined interval and simultaneously therewith disconnecting the other of said transmitters from said antenna and B-power supply during such predetermined interval; a second transmitter of radio frequency signals remotely situated from said first transmitter; a radio receiver located at said second transmitter and responsive to signals radiated by said relaying transmitter; and means connected to said receiver for effecting radiation of signals by said second transmitter during the period of reception of said relaying radio signals.

14. A signal transmission arrangement for a radio guidance system comprising a first transmitter of radio frequency signals; a relaying radio frequency transmitter located at said first transmitter; a common antenna for said first transmitter and said relaying transmitter; a B-power supply located at said first transmitter; means for successively effecting radiation of radio signals by said first and relaying transmitters for predetermined intervals and including a relay unit including a first set of contacts connected to said first transmitter, a second set of contacts connected to said relaying transmitter, a pair. of armatures connected respectively to said antenna and B-power supply, and a solenoid for moving said armatures between said first and second sets of contacts, and mechanism for periodically energizing and deenergizing said solenoid; a sec- 10 0nd transmitter of radio frequency signals remotely situated from said first transmitter; a radio receiver located at said second transmitter and responsive to signals radiated by said relaying transmitter; and means connected to said receiver for effecting radiation of signals by said second transmitter during the period of reception of said relaying radio signals.

- WILLIAM P. LEAR. 

